Sol-gel process for synthesis of nanocrystalline oxides

Patent metadata

Field	Value
Publication number	US-10106432-B2
Application number	US-201414889792-A
Country	US
Kind code	B2
Filing date	May 9, 2014
Priority date	May 9, 2013
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

A Continuous flow synthesis of nanocrystalline metal oxides by rapid sol-gel process is disclosed. The process disclosed uses an impinging microjet micromixer device to obtain the nano crystalline metal oxides. A method of fabricating and assembling the impinging microjet micromixer is also disclosed herewith.

First claim

We claim:

1. A sol-gel process for continuous flow synthesis of a nanocrystalline metal oxide using an impinging jet micromixer, wherein the impinging jet micromixer comprises an inlet for reactant 1 and an inlet for reactant 2 each connected to a metallic block having a microscopic bore, the metallic block is connected to a support plate using a support tension spring and a screw for adjusting an angle of impinging jets, wherein a mixing zone is formed by the impinging jets coming out of the microscopic bore, further wherein an angle between the impinging jets is 70-120 degrees and a ratio of a length of the mixing zone to a thickness of the mixing zone is 0.6-1.2,
the sol-gel process comprises the steps of:
i. pumping a water solution in a solvent and a metal alkoxide solution in the solvent continuously through the inlet for reactant 1 and the inlet for reactant 2 , respectively, followed by mixing, in the mixing zone:
ii. synthesizing a wet gel at a flow rate of 10 to 20 ml/min with a jet diameter of 100-1000 micron and at the angle 70-120 degrees;
iii. ageing the wet gel obtained in step (ii) to provide an aged gel, and
iv. vacuum drying the aged gel at a temperature of 70 to 90° C. for a period of 8 to 12 hours, followed by calcination at a temperature of 350-600° C. to obtain the nanocrystalline metal oxide.

2. The process according to claim 1 , wherein the solvent used is a mixture of methanol and toluene in a toluene to methanol volume ratio of 1.60.

3. The process according to claim 1 , wherein a rate of mixing is faster than a rate of reaction to achieve a homogeneous nucleation.

4. The process according to claim 1 , wherein the metal alkoxide is selected from the group consisting of Zirconium alkoxide, Strontium alkoxide, and Magnesium alkoxide.

5. The process according to claim 1 , wherein the nanocrystalline metal oxide is selected from the group consisting of Zirconium oxide, Strontium oxide, and magnesium oxide.

6. The process according to claim 1 , wherein a molar ratio of metal alkoxide to water in step (i) is 1:2 to 1:5.

7. The process according to claim 1 , wherein the ratio of the length of the mixing zone to the thickness of the mixing zone is 1.

8. The process according to claim 1 , wherein the thickness of the mixing zone is 7.2 to 20.7 μm.

Assignees

• Council Scient Ind Res

Inventors

• Darbha Venkata Ravi Kumar
• Bhagavatula Lakhsmi Vara Prasad
• Kulkarni Amol Arvind

Classifications

• B01F5/0256

  Operations & Transport · mapped topic

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• C01P2004/54

  Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension · CPC title

• C01P2006/14

  Pore volume · CPC title

• B01J19/0093

  Microreactors, e.g. miniaturised or microfabricated reactors (laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027) · CPC title